Wiring pattern of semiconductor integrated circuit device

ABSTRACT

As shown in FIG. 4, a wiring pattern of a semiconductor integrated circuit device of the present invention comprises a wiring portion extending from a connection hole and a connection portion located on the connection hole and having a matching allowance with respect to said connection hole on said wiring portion side being formed wider than a predetermined matching allowance by a predetermined width with which a required yield of successful matching can be assured.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the wiring pattern of a semiconductor integrated circuit device, and more particularly to the technique of matching the allowance between a connection hole such as a contact hole or through hole, and a wiring.

2. Description of the Related Art

Conventionally, the matching allowance between a connecting hole (e.g., a contact hole or a through hole) and a wiring is set equally around the connecting holes, in order to compensate for the deviation which occurs in the step of lithography randomly in every direction. When the deviation is zero, the width of the wiring around the connection hole, the around width H, at the periphery of the connecting hole is formed as shown in FIGS. 1A and 1B. FIGS. 1A and 1B illustrate a connecting hole 11, wiring layer 12, and an inter-layer insulation layer 13.

As is shown in FIG. 1B, a notch S is formed in the wiring layer in the connection hole 11. When electric current flows through the connection hole 11, resistance against the current increases at the section where the notch S is located. The wiring resistance around connection hole 11 (to be called "connection hole resistance" hereinafter) can be substituted with an equivalent circuit shown in FIG. 2, which is designed so that when a deviation between the connection hole 11 and the pattern of the wiring 12 is zero, current paths I₂ and I₂ ' on the wiring extension side become wide.

In reality, however, due to a matching error a in the step of pattern matching, a variety of deviations may occur between the connection hole 11 and the wiring layer 12.

FIGS. 3A to 3C illustrate several examples of matching deviation between the connection hole 11 and the wiring layer 12.

FIG. 3A shows a case where the connection hole 11 deviates in the direction opposite to the wiring extension side. In this case, as the around width B₁ narrows, resistances R₃ and R₃ ' inevitably increase.

However, electrical current i₃, which is affected by the resistances, comprises a very small portion of the total current. Further, as the around width B₂ widens, resistances R₂ and R₂ ' decrease. Therefore, there is little change in connection hole resistance as a whole.

FIG. 3B shows a case where the connection hole 11 deviates in the vertical direction toward the wiring extension side. In this case, around width C₁ narrows and around width C₂ widens. Therefore, resistances (R₂ +R₃) and (R₂ '+R₃ ') respectively increase and decrease, thereby canceling each other, so that the connection hole resistance is only slightly affected, as a whole.

FIG. 3C shows a case where the connection hole 11 deviates towards the wiring extension side. In this case, around width B₂ narrows, and the effective current paths I₂ and I₂ ' narrow, whereby the connection hole resistance inevitably increases. More specifically, current flows through all of resistances r₁, R₂ and R₃. As around width B₂ narrows, currents I₂ and I₂ ' flowing through resistances R₂ and R₂ ' decrease, and current i₁ flowing through resistance r₁, which becomes high due to device structure, increases. Therefore, the matching deviation directly affects the connection hole resistance, and disconnection of the wiring due to heat-emission or electromigration may occur at the notch S.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a wiring pattern of a semiconductor integrated circuit device in which the connection hole resistance does not increase even if matching deviation between a connection hole such as a contact hole or through hole, and a wiring layer occurs.

To achieve the above-mentioned object, the wiring pattern of the semiconductor integrated circuit device according to the present invention comprises a wiring portion extending from the connection hole and a connection portion located above the connection hole and connected to the wiring portion so that it makes an obtuse angle, in which a matching allowance for the connection hole on the wiring portion side is formed wider than the regular matching allowance by predetermined width with which a required yield of successful matching can be assured.

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles the invention.

FIG. 1A is a plane view of the wiring pattern of a conventional semiconductor integrated circuit device;

FIG. 1B is a cross-sectional view of FIG. 1A along the line P-P';

FIG. 2 is a conventional equivalent circuit of the wiring resistance of a wiring near a connection hole, such as a contact hole or hole through hole;

FIGS. 3A-3C are cross-sectional views of examples of conventional matching deviation between the connection hole and the wiring;

FIG. 4 is a plane view of a wiring pattern of a semiconductor integrated circuit device according to an embodiment of the present invention;

FIG. 5 shows a relationship between the matching deviation amount and the connection hole resistance comprising a conventional semiconductor device with the present invention;

FIG. 6 is a plane view showing a wiring pattern of a semiconductor integrated circuit according to a second embodiment of the present invention; and

FIG. 7 is a plane view showing a wiring pattern of a semiconductor integrated circuit according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A wiring pattern of a semiconductor integrated circuit device according to an embodiment of the present invention will be described with reference to the accompanying drawings wherein like reference numerals designate like items and explanations thereof are omitted.

FIG. 4 shows a wiring pattern of a semiconductor integral circuit according to a first embodiment of the present invention, including a semiconductor substrate 21, a connection hole 22, a wiring layer 23, a wiring width A, matching allowances between the connection hole and the wiring layer B and C, a wiring portion P, and a connection portion Q.

The connection hole 22 such as a contact hole or a through hole, is formed in the semiconductor substrate 21, and the wiring layer 23 is formed around the connection hole 22. The wiring layer 2 consists of the wiring portion P, which is a wiring portion extending in on direction from a side of the square-shaped connection hole 22, and connection portion Q, which is a wiring portion located adjacent to the connection hole 22. The matching allowance B on the wiring portion P side of the connection portion Q is formed so that it has a predetermined width, in other words, a width with which a sufficient current path can be obtained when the matching deviation of the wiring layer 23 is set to zero. The matching allowance B on the wiring portion P side is set so that it is a predetermined width wider than the regular matching allowance to cover the necessary matching efficiency. The matching allowance C at the sides other than the wiring portion P side is set to an appropriate width so that the pattern of the wiring layer 23 does not become too large.

For example, suppose that the minimum around width of the wiring portion P side for obtaining a sufficient electric current path is about 1.0 μm. When the required yield of the successful allowance is 3σ (σ is a value for dispersion in the normal distribution), and the predetermined width with which 3σ can be assured is about 0.5 μm, the allowance B on the wiring portion P side should be set to about 1.5 μm to obtain a sufficient current path. When the matching deviation of the wiring is zero, the around width is about 1.5 μm as originally designed for the width of the matching allowance B. Even if the matching deviation of the wiring is as much as 0.5 μm in the direction opposite to the wiring portion P, the around width of about 1.0 μm can be assured.

The matching allowances C for the sides other than the wiring portion P side are set to about 0.7 μm to obtain an around width of, for example, about 0.2 μm at a minimum. This is because, if the width of the matching allowances C is set to the same as that of the matching allowance B, the size of the wiring pattern of the wiring layer 23 around the connection hole 22 becomes very large, thereby lowering the degree of integration. The matching allowances other than that of the wiring portion P side should only be set to a minimally necessary width so that the wiring pattern does not become too large. In this embodiment, the wiring width A is set to about 2 μm, and the size of the connection hole is set to about 3.0×3.0 μm.

According to such a structure, the matching allowance B of the wiring portion P side is set a predetermined width wider than the predetermined allowance so as to the matching deviation even in the case where the wiring layer width deviates in the direction opposite to the wiring portion P side. Specifically, even if the wiring layer 23 deviates in the direction opposite to the wiring portion P side, a sufficient around width can be obtained within the range of the successful yield of matching allowance, so that the contact hole resistance is not increased.

In the meantime, the connection hole resistance where the wiring layer 23 includes the matching allowance B of about 1.5 μm and the matching allowance C of about 0.7 μm was measured and the result is shown in FIG. 5 as represented by straight line II. As represented by the line II, when the amount of deviation in the direction opposite to the wiring portion P side is within 1.0 μm, in other words, the around width is in the range of 0.5-1.5 μm in the wiring layer 23, no increment in the connection hole resistance was detected. Further, the connection hole resistance in the case where the matching allowances for all sides of the connection hole 22 are equally set to about 1.0 μm was measured and the result is also shown in this figure as represented by curve I.

The present invention was applied to a bipolar LSI (A/D converter) having 4,500 elements, and no decrement in the degree of integration was detected.

FIG. 6 shows a wiring pattern of a semiconductor integrated circuit device according to a second embodiment of the present invention.

As shown in FIG. 6, the connection hole 22, such as a contact hole, or through hole is formed on the semiconductor substrate 21, and the wiring layer 23 is formed on the connection hole 22. The wiring layer 23 is made up of a first wiring portion Q, a second wiring portion P, and a third wiring portion R. The contact hole 22 and the first wiring portion Q of the wiring layer 23 are both rectangular. One end of the second wiring portion P is connected to the first side of the first wiring portion Q, the first side being one of the four sides of the rectangular wiring portion Q. The third wiring portion R is triangular in shape and is defined by the first wiring portion Q, the second wiring portion P, and a straight line 24 which passes through one end of the first side and forms an angle of θ where (0<θ<π/2) with reference to that first side. If θ=0, then the wiring pattern 23 of the second embodiment is similar to that of the first embodiment. The matching allowance B of the wiring portion P side is formed wider than a predetermined width to assure a sufficient current path when the matching deviation of matching pattern is set to zero. In detail, the matching allowance B is formed wider than the predetermined matching allowance C by a predetermined width which assures the required yield of successful allowance.

For example, suppose that the minimum around width of the wiring portion P side for obtaining a sufficient electric current path is about 1.0 μm. When the required yield of the successful allowance is 3σ (σ is a value for dispersion in the normal distribution), and the predetermined width with which 3σ can be assured is about 0.5 μm, the allowance B on the wiring portion P side should be set to about 1.5 μm to obtain a sufficient current path. Further, the matching allowances other than the wiring portion P side are designed to be about 0.7 μm so as to obtain an around width of, for example, about 0.2 μm at a minimum. With such a structure, the matching allowance B of wiring portion P is expressed by B=C(1+tanθ), where (0<θ<π/2). This means the matching allowance B is wider than matching allowance C by C.tanθ. Therefore, even if the wiring layer 23 is shifted away from wiring portion P, a sufficiently great around width is ensured as long as angle θ is determined properly. However, the matching allowance B is, in advance, formed wider than the predetermined matching allowance by a predetermined width with which the actual matching deviation can be covered. Therefore, even if the wiring layer 23 deviates in the direction opposite to the wiring portion P side, the necessary around width can be obtained, and therefore the connection hole resistance does not increase.

Lastly, the above-described embodiments include the cases where there is only one wiring portion P. However, the present invention, of course, can be applied in the case where there is more than one wiring portion P, for example, as shown in FIG. 7. In this case also, there will not be any problem if the matching allowances B of each of the wiring portions P is formed wider than a predetermined matching allowance by a width with which a required yield can be assured.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices, shown and described herein. Accordingly, various modifications may be without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

What is claimed is:
 1. A wiring pattern of a semiconductor integrated circuit device, comprising:a first wiring portion formed around a rectangular contact hole and having a rectangular shape, said first wiring portion having first to fourth sides which are adjacent to sides of the contact hole; a second wiring portion having an end portion connected to the first side of the first wiring portion, said second wiring portion having a wiring width narrower than the length of the first side of the first wiring portion; and a third portion defined by the first wiring portion, the second wiring portion, and a straight line which passes through one end of the first side of the first wiring portion and forms an angle of θ where (0<θ<π/2) with reference to the first side of the first wiring portion.
 2. The wiring pattern of a semiconductor integrated circuit device according to claim 1, wherein said contact hole has a square shape.
 3. The wiring pattern of a semiconductor integrated circuit device according to claim 1, wherein said contact hole has a square shape of about 3.0 μm×3.0 μm. 